School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Nature. 2010 Jun 10;465(7299):759-62. doi: 10.1038/nature09069.
Thin liquid films, such as soap bubbles, have been studied extensively for over a century because they are easily formed and mediate a wide range of transport processes in physics, chemistry and engineering. When a bubble on a liquid-gas or solid-gas interface (referred to herein as an interfacial bubble) ruptures, the general expectation is that the bubble vanishes. More precisely, the ruptured thin film is expected to retract rapidly until it becomes part of the interface, an event that typically occurs within milliseconds. The assumption that ruptured bubbles vanish is central to theories on foam evolution and relevant to health and climate because bubble rupture is a source for aerosol droplets. Here we show that for a large range of fluid parameters, interfacial bubbles can create numerous small bubbles when they rupture, rather than vanishing. We demonstrate, both experimentally and numerically, that the curved film of the ruptured bubble can fold and entrap air as it retracts. The resulting toroidal geometry of the trapped air is unstable, leading to the creation of a ring of smaller bubbles. The higher pressure associated with the higher curvature of the smaller bubbles increases the absorption of gas into the liquid, and increases the efficiency of rupture-induced aerosol dispersal.
薄液膜，如肥皂泡，已经被广泛研究了一个多世纪，因为它们很容易形成，并在物理、化学和工程中介导广泛的输运过程。当液体-气体或固体-气体界面上的气泡（本文中称为界面气泡）破裂时，通常的预期是气泡会消失。更准确地说，破裂的薄膜应该迅速缩回，直到它成为界面的一部分，这一事件通常在几毫秒内发生。破裂气泡消失的假设是泡沫演化理论的核心，与健康和气候有关，因为气泡破裂是气溶胶液滴的来源。在这里，我们表明，对于很大范围的流体参数，界面气泡在破裂时可以产生许多小气泡，而不是消失。我们通过实验和数值模拟证明，破裂气泡的弯曲薄膜在缩回时可以折叠并捕获空气。捕获的空气的环形几何形状是不稳定的，导致更小气泡的环的形成。较小气泡的更高曲率相关的更高压力增加了气体向液体中的吸收，并增加了破裂引起的气溶胶分散的效率。
